refactor digest size getter into property, handle the case of unavailable crypto

9 files changed, 69 insertions, 54 deletions

diff --git a/pysnmp/proto/secmod/eso/priv/aesbase.py b/pysnmp/proto/secmod/eso/priv/aesbase.py
index 43bb724b..a8667139 100644
--- a/pysnmp/proto/secmod/eso/priv/aesbase.py
+++ b/pysnmp/proto/secmod/eso/priv/aesbase.py
@@ -68,8 +68,8 @@ class AbstractAesReeder(aes.Aes):
             hashAlgo = md5
         elif authProtocol == hmacsha.HmacSha.serviceID:
             hashAlgo = sha1
-        elif authProtocol in hmacsha2.HmacSha2.hashAlgo:
-            hashAlgo = hmacsha2.HmacSha2.hashAlgo[authProtocol]
+        elif authProtocol in hmacsha2.HmacSha2.hashAlgorithms:
+            hashAlgo = hmacsha2.HmacSha2.hashAlgorithms[authProtocol]
         else:
             raise error.ProtocolError(
                 'Unknown auth protocol %s' % (authProtocol,)
diff --git a/pysnmp/proto/secmod/eso/priv/des3.py b/pysnmp/proto/secmod/eso/priv/des3.py
index 16d770e9..ac082c7f 100644
--- a/pysnmp/proto/secmod/eso/priv/des3.py
+++ b/pysnmp/proto/secmod/eso/priv/des3.py
@@ -47,8 +47,8 @@ class Des3(base.AbstractEncryptionService):
             hashAlgo = md5
         elif authProtocol == hmacsha.HmacSha.serviceID:
             hashAlgo = sha1
-        elif authProtocol in hmacsha2.HmacSha2.hashAlgo:
-            hashAlgo = hmacsha2.HmacSha2.hashAlgo[authProtocol]
+        elif authProtocol in hmacsha2.HmacSha2.hashAlgorithms:
+            hashAlgo = hmacsha2.HmacSha2.hashAlgorithms[authProtocol]
         else:
             raise error.ProtocolError(
                 'Unknown auth protocol %s' % (authProtocol,)
@@ -61,8 +61,8 @@ class Des3(base.AbstractEncryptionService):
             hashAlgo = md5
         elif authProtocol == hmacsha.HmacSha.serviceID:
             hashAlgo = sha1
-        elif authProtocol in hmacsha2.HmacSha2.hashAlgo:
-            hashAlgo = hmacsha2.HmacSha2.hashAlgo[authProtocol]
+        elif authProtocol in hmacsha2.HmacSha2.hashAlgorithms:
+            hashAlgo = hmacsha2.HmacSha2.hashAlgorithms[authProtocol]
         else:
             raise error.ProtocolError(
                 'Unknown auth protocol %s' % (authProtocol,)
diff --git a/pysnmp/proto/secmod/rfc3414/auth/base.py b/pysnmp/proto/secmod/rfc3414/auth/base.py
index 133416b8..37e8c4d7 100644
--- a/pysnmp/proto/secmod/rfc3414/auth/base.py
+++ b/pysnmp/proto/secmod/rfc3414/auth/base.py
@@ -15,8 +15,9 @@ class AbstractAuthenticationService(object):
 
     def localizeKey(self, authKey, snmpEngineID):
         raise error.ProtocolError(errind.noAuthentication)
-    
-    def getTagLen(self):
+
+    @property
+    def digestLength(self):
         raise error.ProtocolError(errind.noAuthentication)
 
     # 7.2.4.1
diff --git a/pysnmp/proto/secmod/rfc3414/auth/hmacmd5.py b/pysnmp/proto/secmod/rfc3414/auth/hmacmd5.py
index 13b27e10..907f1ce6 100644
--- a/pysnmp/proto/secmod/rfc3414/auth/hmacmd5.py
+++ b/pysnmp/proto/secmod/rfc3414/auth/hmacmd5.py
@@ -32,7 +32,8 @@ class HmacMd5(base.AbstractAuthenticationService):
     def localizeKey(self, authKey, snmpEngineID):
         return localkey.localizeKeyMD5(authKey, snmpEngineID)
 
-    def getTagLen(self):
+    @property
+    def digestLength(self):
         return 12
 
     # 6.3.1
diff --git a/pysnmp/proto/secmod/rfc3414/auth/hmacsha.py b/pysnmp/proto/secmod/rfc3414/auth/hmacsha.py
index 16cb2149..3ac7c33b 100644
--- a/pysnmp/proto/secmod/rfc3414/auth/hmacsha.py
+++ b/pysnmp/proto/secmod/rfc3414/auth/hmacsha.py
@@ -32,7 +32,8 @@ class HmacSha(base.AbstractAuthenticationService):
     def localizeKey(self, authKey, snmpEngineID):
         return localkey.localizeKeySHA(authKey, snmpEngineID)
 
-    def getTagLen(self):
+    @property
+    def digestLength(self):
         return 12
 
     # 7.3.1
diff --git a/pysnmp/proto/secmod/rfc3414/priv/des.py b/pysnmp/proto/secmod/rfc3414/priv/des.py
index e38239ad..dd07d4d0 100644
--- a/pysnmp/proto/secmod/rfc3414/priv/des.py
+++ b/pysnmp/proto/secmod/rfc3414/priv/des.py
@@ -45,8 +45,8 @@ class Des(base.AbstractEncryptionService):
             hashAlgo = md5
         elif authProtocol == hmacsha.HmacSha.serviceID:
             hashAlgo = sha1
-        elif authProtocol in hmacsha2.HmacSha2.hashAlgo:
-            hashAlgo = hmacsha2.HmacSha2.hashAlgo[authProtocol]
+        elif authProtocol in hmacsha2.HmacSha2.hashAlgorithms:
+            hashAlgo = hmacsha2.HmacSha2.hashAlgorithms[authProtocol]
         else:
             raise error.ProtocolError(
                 'Unknown auth protocol %s' % (authProtocol,)
@@ -58,8 +58,8 @@ class Des(base.AbstractEncryptionService):
             hashAlgo = md5
         elif authProtocol == hmacsha.HmacSha.serviceID:
             hashAlgo = sha1
-        elif authProtocol in hmacsha2.HmacSha2.hashAlgo:
-            hashAlgo = hmacsha2.HmacSha2.hashAlgo[authProtocol]
+        elif authProtocol in hmacsha2.HmacSha2.hashAlgorithms:
+            hashAlgo = hmacsha2.HmacSha2.hashAlgorithms[authProtocol]
         else:
             raise error.ProtocolError(
                 'Unknown auth protocol %s' % (authProtocol,)
diff --git a/pysnmp/proto/secmod/rfc3414/service.py b/pysnmp/proto/secmod/rfc3414/service.py
index d0a88c9c..714595c9 100644
--- a/pysnmp/proto/secmod/rfc3414/service.py
+++ b/pysnmp/proto/secmod/rfc3414/service.py
@@ -438,7 +438,7 @@ class SnmpUSMSecurityModel(AbstractSecurityModel):
 
             # extra-wild hack to facilitate BER substrate in-place re-write
             securityParameters.setComponentByPosition(
-                4, '\x00' * authHandler.getTagLen()
+                4, '\x00' * authHandler.digestLength
             )
 
             debug.logger & debug.flagSM and debug.logger(
diff --git a/pysnmp/proto/secmod/rfc3826/priv/aes.py b/pysnmp/proto/secmod/rfc3826/priv/aes.py
index 734e9643..d390f455 100644
--- a/pysnmp/proto/secmod/rfc3826/priv/aes.py
+++ b/pysnmp/proto/secmod/rfc3826/priv/aes.py
@@ -78,8 +78,8 @@ class Aes(base.AbstractEncryptionService):
             hashAlgo = md5
         elif authProtocol == hmacsha.HmacSha.serviceID:
             hashAlgo = sha1
-        elif authProtocol in hmacsha2.HmacSha2.hashAlgo:
-            hashAlgo = hmacsha2.HmacSha2.hashAlgo[authProtocol]
+        elif authProtocol in hmacsha2.HmacSha2.hashAlgorithms:
+            hashAlgo = hmacsha2.HmacSha2.hashAlgorithms[authProtocol]
         else:
             raise error.ProtocolError(
                 'Unknown auth protocol %s' % (authProtocol,)
@@ -91,8 +91,8 @@ class Aes(base.AbstractEncryptionService):
             hashAlgo = md5
         elif authProtocol == hmacsha.HmacSha.serviceID:
             hashAlgo = sha1
-        elif authProtocol in hmacsha2.HmacSha2.hashAlgo:
-            hashAlgo = hmacsha2.HmacSha2.hashAlgo[authProtocol]
+        elif authProtocol in hmacsha2.HmacSha2.hashAlgorithms:
+            hashAlgo = hmacsha2.HmacSha2.hashAlgorithms[authProtocol]
         else:
             raise error.ProtocolError(
                 'Unknown auth protocol %s' % (authProtocol,)
diff --git a/pysnmp/proto/secmod/rfc7860/auth/hmacsha2.py b/pysnmp/proto/secmod/rfc7860/auth/hmacsha2.py
index 60453c53..ddf24b51 100644
--- a/pysnmp/proto/secmod/rfc7860/auth/hmacsha2.py
+++ b/pysnmp/proto/secmod/rfc7860/auth/hmacsha2.py
@@ -7,15 +7,16 @@
 try:
     from hashlib import sha224, sha256, sha384, sha512
     import hmac
+    SHA = True
 except ImportError:
-    import logging
-    logging.debug('SHA-2 HMAC authentication unavailable', exc_info=True)
+    SHA = False
 
 from pyasn1.type import univ
 from pysnmp.proto.secmod.rfc3414.auth import base
 from pysnmp.proto.secmod.rfc3414 import localkey
 from pysnmp.proto import errind, error
 
+
 # 7.2.4
 
 class HmacSha2(base.AbstractAuthenticationService):
@@ -23,34 +24,34 @@ class HmacSha2(base.AbstractAuthenticationService):
     sha256ServiceID = (1, 3, 6, 1, 6, 3, 10, 1, 1, 5)  # usmHMAC192SHA256AuthProtocol
     sha384ServiceID = (1, 3, 6, 1, 6, 3, 10, 1, 1, 6)  # usmHMAC256SHA384AuthProtocol
     sha512ServiceID = (1, 3, 6, 1, 6, 3, 10, 1, 1, 7)  # usmHMAC384SHA512AuthProtocol
-    keyLength = {
-        sha224ServiceID : 28,
-        sha256ServiceID : 32,
-        sha384ServiceID : 48,
-        sha512ServiceID : 64
+    keyLengths = {
+        sha224ServiceID: 28,
+        sha256ServiceID: 32,
+        sha384ServiceID: 48,
+        sha512ServiceID: 64
     }
-    tagLength = {
-        sha224ServiceID : 16,
-        sha256ServiceID : 24,
-        sha384ServiceID : 32,
-        sha512ServiceID : 48
+    digestLengths = {
+        sha224ServiceID: 16,
+        sha256ServiceID: 24,
+        sha384ServiceID: 32,
+        sha512ServiceID: 48
     }
-    hashAlgo = {
-        sha224ServiceID : sha224,
-        sha256ServiceID : sha256,
-        sha384ServiceID : sha384,
-        sha512ServiceID : sha512
+    hashAlgorithms = {
+        sha224ServiceID: sha224,
+        sha256ServiceID: sha256,
+        sha384ServiceID: sha384,
+        sha512ServiceID: sha512
     }
     
     __ipad = [0x36] * 64
     __opad = [0x5C] * 64
     
     def __init__(self, oid):
-        if not oid in HmacSha2.hashAlgo:
-            raise error.ProtocolError('no such SHA-2 authentication algorithm', oid)
-        self.__hashAlgo = HmacSha2.hashAlgo[oid]
-        self.__tagLength = HmacSha2.tagLength[oid]
-        self.__placeHolder = univ.OctetString((0,) * self.__tagLength).asOctets()
+        if oid not in self.hashAlgorithms:
+            raise error.ProtocolError('No SHA-2 authentication algorithm %s available' % (oid,))
+        self.__hashAlgo = self.hashAlgorithms[oid]
+        self.__digestLength = self.digestLengths[oid]
+        self.__placeHolder = univ.OctetString((0,) * self.__digestLength).asOctets()
 
     def hashPassphrase(self, authKey):
         return localkey.hashPassphrase(authKey, self.__hashAlgo)
@@ -58,48 +59,59 @@ class HmacSha2(base.AbstractAuthenticationService):
     def localizeKey(self, authKey, snmpEngineID):
         return localkey.localizeKey(authKey, snmpEngineID, self.__hashAlgo)
 
-    def getTagLen(self):
-        return self.__tagLength
+    @property
+    def digestLength(self):
+        return self.__digestLength
 
     # 7.3.1
     def authenticateOutgoingMsg(self, authKey, wholeMsg):
+        if not SHA:
+            raise error.StatusInformation(
+                errorIndication=errind.authenticationError
+            )
+
         # 7.3.1.1
-        l = wholeMsg.find(self.__placeHolder)
-        if l == -1:
+        location = wholeMsg.find(self.__placeHolder)
+        if location == -1:
             raise error.ProtocolError('Can\'t locate digest placeholder')
-        wholeHead = wholeMsg[:l]
-        wholeTail = wholeMsg[l + self.__tagLength:]
+        wholeHead = wholeMsg[:location]
+        wholeTail = wholeMsg[location + self.__digestLength:]
 
         # 7.3.1.2, 7.3.1.3
         mac = hmac.new(authKey.asOctets(), wholeMsg, self.__hashAlgo)
 
         # 7.3.1.4
-        mac = mac.digest()[:self.__tagLength]
+        mac = mac.digest()[:self.__digestLength]
 
         # 7.3.1.5 & 6
         return wholeHead + mac + wholeTail
 
     # 7.3.2
     def authenticateIncomingMsg(self, authKey, authParameters, wholeMsg):
+        if not SHA:
+            raise error.StatusInformation(
+                errorIndication=errind.authenticationError
+            )
+
         # 7.3.2.1 & 2
-        if len(authParameters) != self.__tagLength:
+        if len(authParameters) != self.__digestLength:
             raise error.StatusInformation(
                 errorIndication=errind.authenticationError
             )
 
         # 7.3.2.3
-        l = wholeMsg.find(authParameters.asOctets())
-        if l == -1:
+        location = wholeMsg.find(authParameters.asOctets())
+        if location == -1:
             raise error.ProtocolError('Can\'t locate digest in wholeMsg')
-        wholeHead = wholeMsg[:l]
-        wholeTail = wholeMsg[l + self.__tagLength:]
+        wholeHead = wholeMsg[:location]
+        wholeTail = wholeMsg[location + self.__digestLength:]
         authenticatedWholeMsg = wholeHead + self.__placeHolder + wholeTail
 
         # 7.3.2.4
         mac = hmac.new(authKey.asOctets(), authenticatedWholeMsg, self.__hashAlgo)
 
         # 7.3.2.5
-        mac = mac.digest()[:self.__tagLength]
+        mac = mac.digest()[:self.__digestLength]
 
         # 7.3.2.6
         if mac != authParameters: